Recent Advances in Molecular Mechanisms of Cancer Immunotherapy

Cancer is among the current leading causes of death worldwide, despite the novel advances that have been made toward its treatment, it is still considered a major public health concern. Considering both the serious impact of cancer on public health and the significant side effects and complications of conventional therapeutic options, the current strategies towards targeted cancer therapy must be enhanced to avoid undesired toxicity. Cancer immunotherapy has become preferable among researchers in recent years compared to conventional therapeutic options, such as chemotherapy, surgery, and radiotherapy. The understanding of how to control immune checkpoints, develop therapeutic cancer vaccines, genetically modify immune cells as well as enhance the activation of antitumor immune response led to the development of novel cancer treatments. In this review, we address recent advances in cancer immunotherapy molecular mechanisms. Different immunotherapeutic approaches are critically discussed, focusing on the challenges, potential risks, and prospects involving their use.

Mathematical Prostate Cancer Evolution: Effect of Immunotherapy Based on Controlled Vaccination Strategy

Basic immunology research over several decades has led to an improved understanding of tumour recognition by components of the immune system and mechanism of tumour evasion from immune detection. These findings have ultimately led to creating antitumour immunotherapies in patients with different kind of cancer including prostate cancer. The increasing number of reports confirms that immune-based therapies have clinical benefit in patients with prostate cancer with potentially less toxicity in comparison with traditional systemic treatments including surgical resection, chemotherapy, or radiotherapy in various forms. This review focuses on the possibility of modulation of the optimal immunotherapy based on vaccination strategy adopted to individual patients in order to increase quality and quantity of their life.

miR‑589‑5p is downregulated in prostate cancer and regulates tumor cell viability and metastasis by targeting CCL‑5

Prostate cancer is one of the most common human malignancies, which represents a serious threat to health, and microRNAs (miRNAs/miRs) have been reported to be closely associated with the progression and development of prostate cancer. The present study aimed to investigate the expression patterns, functions and underlying mechanisms of miR‑589‑5p in prostate cancer. The results demonstrated that the expression levels of miR‑589‑5p were downregulated in prostate cancer tissues and cell lines. Overexpression of miR‑589‑5p inhibited cell viability, migration and invasion in prostate cancer cells. Subsequently, chemokine (C‑C motif) ligand 5 (CCL‑5) was identified as a direct target gene of miR‑589‑5p, which was highly expressed at the mRNA and protein levels in prostate cancer tissues and cells. Furthermore, CCL‑5 mRNA was negatively correlated with miR‑589‑5p expression in prostate cancer tissues. Silencing CCL‑5 promoted the apoptosis, and inhibited the migration and invasion of prostate cancer cells. Taken together, these results indicated that miR‑589‑5p may act as a tumor suppressor in prostate cancer by targeting CCL‑5, thus suggesting that miR‑589‑5p may be a novel and reliable molecular marker for the diagnosis and prognosis of prostate cancer.

Recent advances in nanomaterial-based synergistic combination cancer immunotherapy

This review aims to summarize various synergistic combination cancer immunotherapy strategies based on nanomaterials.

Therapeutic Cancer Vaccines

Cancer is one of the major leading death causes of diseases. Prevention and treatment of cancer is an important way to decrease the incidence of tumorigenesis and prolong patients' lives. Subversive achievements on cancer immunotherapy have recently been paid much attention after many failures in basic and clinical researches. Based on deep analysis of genomics and proteomics of tumor antigens, a variety of cancer vaccines targeting tumor antigens have been tested in preclinical and human clinical trials. Many therapeutic cancer vaccines alone or combination with other conventional treatments for cancer obtained spectacular efficacy, indicating the tremendously potential application in clinic. With the illustration of underlying mechanisms of cancer immune regulation, valid, controllable, and persistent cancer vaccines will play important roles in cancer treatment, survival extension and relapse and cancer prevention. This chapter mainly summarizes the recent progresses and developments on cancer vaccine research and clinical application, thus exploring the existing obstacles in cancer vaccine research and promoting the efficacy of cancer vaccine.

Survivin and PSMA Loaded Dendritic Cell Vaccine for the Treatment of Prostate Cancer

Dendritic cell (DC)-based vaccines are a promising therapeutic modality for cancer. Results from recent trials and approval of the first DC vaccine by the U.S. Food and Drugs Administration for prostate cancer have paved the way for DC-based vaccines. A total of 21 hormone refractory prostate cancer (HRPC) patients with a life expectancy >3 months were randomised into two groups. DC loaded with recombinant Prostate Specific Membrane Antigen (rPSMA) and recombinant Survivin (rSurvivin) peptides was administered as an subcutaneous (s.c.) injection (5×10(6) cells). Docetaxel (75 mg/m(2) intravenous (i.v.)) and prednisone (5 mg, bis in die (b.i.d.)) served as control. Clinical and immunological responses were evaluated. Primary endpoints were safety and feasibility; secondary endpoint was overall survival. Responses were evaluated on day 15, day 30, day 60, and day 90. DC vaccination was well tolerated with no signs of grade 2 toxicity. DC vaccination induced delayed-type hypersensitivity reactivity and an immune response in all patients. Objective Response Rate (ORR) by Response Evaluation Criteria in Solid Tumours (RECIST) was 72.7% (8/11) versus 45.4 (5/11) in the docetaxel arm and immune related response criteria (irRC) was 54.5% (6/11) compared with 27.2% (3/11) in the control arm. The DC arm showed stable disease (SD) in 6 patients, progressive disease (PD) in 3 patients, and partial remission (PR) in two patients compared to SD in 5 patients, PD in 6 patients, and PR in none in the docetaxel arm. There was a cellular response, disease stabilization, no adverse events, and partial remission with the rPSMA and rSurvivin primed DC vaccine.

Materials that harness and modulate the immune system

Recently, biomaterial scientists have married materials engineering and immunobiology to conceptualize new immunomodulatory materials. This special class of biomaterials can modulate and harness the innate properties of immune functionality for enhanced therapeutic efficacy. Generally, two fundamental strategies are followed in the design of immunomodulatory biomaterials: (1) immuno-evasive (immuno-mimetic, immuno-suppressing, or immuno-inert) biomaterials and (2) immuno-activating or immuno-enhancing biomaterials. This article highlights the development and application of a number of immunomodulatory materials, categorized by these two general approaches.

Verification of multimarkers for detection of early stage diabetic retinopathy using multiple reaction monitoring

Diabetic retinopathy (DR) is a complication of diabetes and 80% of diabetes mellitus (DM) patients whose DM duration is over 10 years can be expected to suffer with DR. The diagnosis of DR depends on an ophthalmological examination, and no molecular methods of screening DR status exist. Nonproliferative diabetic retinopathy (NPDR) is the early DR which is hard to be noticed in early NPDR, showing significant cause of adult blindness in type 2 diabetes patients. Protein biomarkers have been valuable in the diagnosis of disease and the use of multiple biomarkers has been suggested to overcome the low specificity of single ones. For biomarker development, multiple reaction monitoring (MRM) has been spotlighted as an alternative method to quantify target proteins with no need for immunoassay. In this study, 54 candidate DR marker proteins from a previous study were verified by MRM in plasma samples from NPDR patients in 3 stages (mild, moderate and severe; 15 cases each) and diabetic patients without retinopathy (15 cases) as a control. Notably, 27 candidate markers distinguished moderate NPDR from type 2 diabetic patients with no diabetic retinopathy, generating AUC values (>0.7). Specifically, 28 candidate proteins underwent changes in expression as type 2 diabetic patients with no diabetic retinopathy progressed to mild and moderate NPDR. Further, a combination of 4 markers from these 28 candidates had the improved specificity in distinguishing moderate NPDR from type 2 diabetic patients with no diabetic retinopathy, yielding a merged AUC value of nearly 1.0. We concluded that MRM is a fast, robust approach of multimarker panel determination and an assay platform that provides improved specificity compared with single biomarker assay systems.

Dendritic cell based PSMA immunotherapy for prostate cancer using a CD40-targeted adenovirus vector

Human prostate tumor vaccine and gene therapy trials using ex vivo methods to prime dendritic cells (DCs) with prostate specific membrane antigen (PSMA) have been somewhat successful, but to date the lengthy ex vivo manipulation of DCs has limited the widespread clinical utility of this approach. Our goal was to improve upon cancer vaccination with tumor antigens by delivering PSMA via a CD40-targeted adenovirus vector directly to DCs as an efficient means for activation and antigen presentation to T-cells. To test this approach, we developed a mouse model of prostate cancer by generating clonal derivatives of the mouse RM-1 prostate cancer cell line expressing human PSMA (RM-1-PSMA cells). To maximize antigen presentation in target cells, both MHC class I and TAP protein expression was induced in RM-1 cells by transduction with an Ad vector expressing interferon-gamma (Ad5-IFNγ). Administering DCs infected ex vivo with CD40-targeted Ad5-huPSMA, as well as direct intraperitoneal injection of the vector, resulted in high levels of tumor-specific CTL responses against RM-1-PSMA cells pretreated with Ad5-IFNγ as target cells. CD40 targeting significantly improved the therapeutic antitumor efficacy of Ad5-huPSMA encoding PSMA when combined with Ad5-IFNγ in the RM-1-PSMA model. These results suggest that a CD-targeted adenovirus delivering PSMA may be effective clinically for prostate cancer immunotherapy.

A chemically induced vaccine strategy for prostate cancer

Here we report the design and evaluation of a bifunctional, small molecule switch that induces a targeted immune response against tumors in vivo. A high affinity ligand for prostate specific membrane antigen (PSMA) was conjugated to a hapten that binds dinitrophenyl (DNP)-specific antibodies. When introduced into hu-PBL-NOD/SCID mice previously immunized with a KLH-DNP immunogen, this conjugate induced a targeted antibody-dependent cellular cytotoxicity (ADCC) response to PSMA-expressing tumor cells in a mouse xenograft model. The ability to create a small molecule inducible antibody response against self-antigens using endogenous non-autoreactive antibodies may provide advantages over the autologous immune response generated by conventional vaccines in certain therapeutic settings.

Enhancing cellular cancer vaccines

Various strategies have been used to generate cellular cancer vaccines with the expectation that they will become an effective part of the overall management of cancer patients. However, with few notable exceptions, immunization has not resulted in significant long-term therapeutic benefits. Tumor growth has continued and patient survival has been at best only modestly prolonged. One possible explanation is that as only a small proportion of the constituents of malignant cells are "tumor specific" and the vast majority are the products of nonantigenic, normal "housekeeping" genes, the immune response in patients immunized with cellular cancer vaccines is not sufficient to result in tumor rejection. Here, we review and characterize various types of cellular cancer vaccines. In addition, in a mouse breast cancer model system, we describe a unique strategy designed to enrich cellular vaccines for cells that induce tumor immunity. Numerous advantages and disadvantages of cancer immunotherapy with cellular vaccines are also presented.

Diffuse primary leptomeningeal melanocytosis in a patient receiving a novel cancer cell vaccine for prostate cancer

A 75-year-old man, undergoing treatment for metastatic prostate cancer with a novel cancer cell vaccine, presented with a 4 week history of poor balance, gait disturbance and cognitive decline. Blood tests including HIV and onconeuronal and voltage gated potassium channel antibodies were normal. Computed tomography and two magnetic resonance images of the brain showed possible non-specific meningeal or vascular enhancement. Two cerebrospinal fluid analyses, including cytology, were negative, other than six lymphocytes in the former. Despite intravenous aciclovir and dexamethasone the patient deteriorated over 16 days, with worsening confusion and involuntary movements, and died. Postmortem examination showed that the leptomeninges overlying the brain and spinal cord were diffusely infiltrated by a melanocytosis with a focal area of melanomatosis. Moreover, there were two sites of metastases of a highly malignant clone present in the pulmonary parenchyma.

TRIAL REGISTRATION NUMBER

NCT00133224.

DNA vaccines: developing new strategies against cancer

Due to their rapid and widespread development, DNA vaccines have entered into a variety of human clinical trials for vaccines against various diseases including cancer. Evidence that DNA vaccines are well tolerated and have an excellent safety profile proved to be of advantage as many clinical trials combines the first phase with the second, saving both time and money. It is clear from the results obtained in clinical trials that such DNA vaccines require much improvement in antigen expression and delivery methods to make them sufficiently effective in the clinic. Similarly, it is clear that additional strategies are required to activate effective immunity against poorly immunogenic tumor antigens. Engineering vaccine design for manipulating antigen presentation and processing pathways is one of the most important aspects that can be easily handled in the DNA vaccine technology. Several approaches have been investigated including DNA vaccine engineering, co-delivery of immunomodulatory molecules, safe routes of administration, prime-boost regimen and strategies to break the immunosuppressive networks mechanisms adopted by malignant cells to prevent immune cell function. Combined or single strategies to enhance the efficacy and immunogenicity of DNA vaccines are applied in completed and ongoing clinical trials, where the safety and tolerability of the DNA platform are substantiated. In this review on DNA vaccines, salient aspects on this topic going from basic research to the clinic are evaluated. Some representative DNA cancer vaccine studies are also discussed.

Immunological evaluation of personalized peptide vaccination monotherapy in patients with castration-resistant prostate cancer

We previously reported that personalized peptide vaccine (PPV) therapy in combination with leutenizing hormone-releasing hormone (LH-RH) analog and estramustine phosphate in certain cases is safe and capable of inducing both immune responses and clinical responses for metastatic castration-resistant prostate cancer (CRPC) patients. In the present study, PPV monotherapy was given to CRPC patients. Twenty-three patients with metastatic CRPC were treated with PPV without any additional treatment modalities, including LH-RH analogs. Samples were analyzed for peptide-specific cytotoxic T-lymphocyte (CTL) precursor analysis and peptide-reactive IgG. Toxicity and immunological and clinical responses were assessed on a three-monthly basis. Seventeen patients were available for immunological and clinical evaluation. The vaccines were well tolerated, with grade 3 erythema at injection sites in only one patient. Augmentation of CTL or IgG responses to at least one of the peptides was observed in six of 17 (35%) and 15 of 17 (88%) patients tested, respectively. Among 57 peptides used, 9 and 36 peptides induced CTL and IgG responses, respectively. Delayed-type hypersensitivity reaction was observed in eight of 17 patients. More than 30% prostate-specific antigen (PSA) decline was observed in four of 17 patients. Of these, one patient achieved a complete PSA response and another patient showed a partial PSA response with profound shrinking of lymph node metastases and prostate. The overall median survival time was 24 months (range, 5-37 months). These results suggest that PPV monotherapy appears to be safe and capable of inducing peptide-specific immune responses and clinical responses in CRPC patients. This trial was registered with University Hospital Medical Information Network (UMIN) number R000003339.

Emerging concepts in biomarker discovery; the US-Japan Workshop on Immunological Molecular Markers in Oncology

Supported by the Office of International Affairs, National Cancer Institute (NCI), the "US-Japan Workshop on Immunological Biomarkers in Oncology" was held in March 2009. The workshop was related to a task force launched by the International Society for the Biological Therapy of Cancer (iSBTc) and the United States Food and Drug Administration (FDA) to identify strategies for biomarker discovery and validation in the field of biotherapy. The effort will culminate on October 28th 2009 in the "iSBTc-FDA-NCI Workshop on Prognostic and Predictive Immunologic Biomarkers in Cancer", which will be held in Washington DC in association with the Annual Meeting. The purposes of the US-Japan workshop were a) to discuss novel approaches to enhance the discovery of predictive and/or prognostic markers in cancer immunotherapy; b) to define the state of the science in biomarker discovery and validation. The participation of Japanese and US scientists provided the opportunity to identify shared or discordant themes across the distinct immune genetic background and the diverse prevalence of disease between the two Nations. Converging concepts were identified: enhanced knowledge of interferon-related pathways was found to be central to the understanding of immune-mediated tissue-specific destruction (TSD) of which tumor rejection is a representative facet. Although the expression of interferon-stimulated genes (ISGs) likely mediates the inflammatory process leading to tumor rejection, it is insufficient by itself and the associated mechanisms need to be identified. It is likely that adaptive immune responses play a broader role in tumor rejection than those strictly related to their antigen-specificity; likely, their primary role is to trigger an acute and tissue-specific inflammatory response at the tumor site that leads to rejection upon recruitment of additional innate and adaptive immune mechanisms. Other candidate systemic and/or tissue-specific biomarkers were recognized that might be added to the list of known entities applicable in immunotherapy trials. The need for a systematic approach to biomarker discovery that takes advantage of powerful high-throughput technologies was recognized; it was clear from the current state of the science that immunotherapy is still in a discovery phase and only a few of the current biomarkers warrant extensive validation. It was, finally, clear that, while current technologies have almost limitless potential, inadequate study design, limited standardization and cross-validation among laboratories and suboptimal comparability of data remain major road blocks. The institution of an interactive consortium for high throughput molecular monitoring of clinical trials with voluntary participation might provide cost-effective solutions.